In a known arrangement for tensioning the saw chain of a chain saw, the drive member is a tensioning bolt extending parallel to the cutter bar and the output member is an entrainment bolt extending radially to the shaft of the tensioning bolt. The tensioning bolt is arranged very close to the housing and to the cutter bar of the chain saw so that the head of the bolt is hardly visible from the outside and access thereto is difficult because parts of the chain saw are arranged so close thereto. Therefore, it is not possible or only very difficult to insert a screwdriver in the slot of the bolt to adjust the tension of the saw chain. Furthermore, there is very little room for the operator to position the hand to rotate the screwdriver so that an adjustment is made very difficult and takes a relatively large amount of time to perform.